1. Field of the Invention
This invention relates generally to the field of dishwasher pumps and more particularly to a pump having an improved particle chopper system.
2. Description of the Related Art
It is well know to provide a dishwasher with a rotating blade or cutter for chopping or sizing relatively large food particles into smaller particles. A typical dishwasher chopping system is disclosed by Cushing et al, in U.S. Pat. No. 3,434,671, issued Mar. 25, 1969. This patent teaches macerating means for a dishwashing pump having a single blade extending outward along a generally radial line and having a connection to the drive shaft of the drive motor. The blade, which includes a cutting edge, is closely spaced from a grid-like grading element at the pump inlet and is operable for macerating or chopping food particles. The blade is attached to the shaft of the drive motor for rotation therewith.
Hahn et al, in U.S. Pat. No. 3,981,456 issued Sep. 21, 1976, and Ziegler, in U.S. Pat. No. 4,201,345 issued May 6, 1980, each disclose a cutter formed from wire and attached to the shaft of the drive motor for rotation thereby. The wire cutter is rotated adjacent a grading element or screen having grid-like openings for effecting the maceration or chopping of food particles.
Dingier et al, in U.S. Pat. No. 4,350,306 issued Sept. 21, 1982, teach a combination recirculating and drain pump construction with a soft food disposer having a chopper blade. The chopper blade is mounted to a wash impeller and is supported immediately upstream and adjacent to a filter screen. The chopper blade along with the wash impeller is secured to a motor drive shaft via a threaded fastener.
Jordan et al., in U.S. Pat. No. 4,795,102, issued May 15, 1984, discloses a dishwasher pump which includes a particle cutter for cutting food particles. The particle cutter is positively secured or mounted to a drain pump impeller and is supported adjacent square apertures provided in a chopper disc or plate. The drain pump is secured to a pump drive shaft. Food particles are chopped by the particle cutter and pass through the apertures into the drain pump so that they may be pumped by the drain pump to an external drain.
The prior art has thus shown a number of different cutters usable with dishwasher pumps to effect comminution or chopping of food and other particles carried by the dishwashing liquid. All of the prior art dishwasher chopping system disclose show a chopping blade which is supported and securely attached to a rotation drive shaft or a rotating element secured to the drive shaft.
The present invention provides a dishwasher having a wash chamber including a sump. A pump having a rotating element is supported within a pump housing wherein the pump is adapted to draw liquid from the sump through an inlet area and then pump liquid to the wash chamber. A particle chopping assembly is supported in the inlet area upstream of the rotating element, the particle sizing assembly including a particle screen rotatably supporting a chopping blade. The chopping blade is detachably coupled to the rotating element for co-rotation therewith.
The particle chopping assembly may further include a drive shaft which is rotatably supported on the particle screen and which drivingly supports the chopping blade. The drive shaft has a coupling end which detachably couples to the rotating element. The coupling between the chopping blade and the rotating element is capable of accommodating axial tolerance with regard to the axial position of the rotating element.
The present invention further is directed to a method for assembling a dishwasher which includes a sump. The method of assembly includes assembling a chopping assembly including a particle screen, a drive shaft and a chopping blade wherein the drive shaft driving supports the chopping blade and is rotatably secured to the particle screen. The chopping assembly is secured within the sump. A pump assembly including a motor and impeller is connected to the sump such that a drive extension of the impeller is drivingly coupled to the chopping assembly. Alternatively, the pump assembly may be connected to the sump before the chopping assembly.